1. Field of the Invention
The present invention relates to a navigation system in which a route search is performed by using a navigation function and a road placed in a facility of a private land is connected to a retrieved route to perform a door-to-door route guidance.
2. Description of Related Art
FIG. 1 shows a conventional navigation apparatus, for example, disclosed in the Published Unexamined Japanese Patent Application H7-93696 (1995). In FIG. 1, 1 indicates a global positioning system (GPS) receiver for receiving electric wave from a GPS satellite. Reference numeral 2 indicates a position detecting means for detecting a position of a driver""s car. Reference numeral 3 indicates a storing means, comprising a CD-ROM or the like, for storing for-navigation location map data. Reference numeral 4 indicates a display computer for displaying a specific piece of location map data read out from the storing unit 3 on a display means 5 which comprises a liquid crystal display (LCD) or the like. A current position of the driver""s car is included in the specific piece of location map data. Reference numeral 6 indicates an operating means comprising a cursor moving key or the like.
Next, operation of the navigation apparatus illustrated in FIG. 1 is described.
Electric wave transmitted from the GPS satellite is received in the GPS receiver 1, a current position of the driver""s car is detected in the position detecting means 2 in which the received electric wave is received, a specific piece of location map data, in which the current position of the driver""s car is included, is selected from the for-navigation location map data stored in advance in the storing unit 3 and is read out by the display computer 4, and a location map indicated by the specific piece of location map data is displayed on the displaying means 5 with a prescribed mark indicating the current position of the driver""s car.
To perform a route guidance to each of a plurality of destinations, a destination setting list, in which both a location map code allocated to a location map of a peripheral area of one destination and coordinates of the destination in the location map are included, is stored in the storing means 3 for each of the destinations. When a desired destination is set by a driver who operates the operating means 6, the destination setting list of the desired destination is read out from the storing means 3 in the display computer 4, location map data corresponding to the location map code of the destination setting list is read out from the storing means 3 in the display computer 4, a location map indicated by the location map data is displayed on the displaying means 5, a guiding route to the desired destination is determined in the display computer 4 according to the read-out location map data, and the guiding route is displayed in the location map displayed on the displaying means 5.
Because the conventional navigation map has the above configuration, information, which indicates roads placed in each facility and is obtained according to the destination search, is only composed of pieces of point information such as latitudes and longitudes. In this case, a driver is not guided to any road other than roads (that is, public roads respectively having a width wider than a prescribed width) of the location map data stored in the storing means 3. Therefore, as shown in FIG. 2, the driver is guided to only a position P of a public road nearest to a destination O placed in a facility M, and a driver""s car is moved from this final guided position P to the destination 0 of the facility M according to the driver""s judgment. Therefore, in cases where an entrance I of the facility M, which has a large area, is placed far away from the final guided position P, it is difficult to reach the entrance I and to reach the destination 0 of the facility M.
Also, because there is usually no location map for driving the car in private land with a large area, it is impossible to correct the position of the driver""s car according to a map matching with a location map of the private land. Thus there is a problem that positional precision for the driver s car is low. Also, in cases where all roads of a facility are indicated by road-in-facility data, a large volume of road-in-facility data is required. Therefore, there is another problem that it is not proper in practice to use the road-in-facility data.
The present invention is provided to solve the above problems, and an object of the present invention is to provide a navigation apparatus in which the search calculation of a guiding route to roads placed in a facility in private land is performed to guide a car to a door of a building of the facility or to guide a car to a recommended parking position of the facility and in which a map matching is possible in the driving of the car in the private land, which has a comparatively wide site, to improve positional precision of the driver""s car.
A navigation apparatus according to the present invention comprises a GPS receiver for receiving electric wave from a GPS satellite, a position detecting means for detecting a position of a driver""s car according to the received electric wave output from the GPS receiver, a storing means for storing for-navigation location map data, an information taking-in means for taking-in facility information which indicates roads placed in a facility and is supplied from the outside, and a displaying means for displaying a location map according to the facility information read out from the information taking-in means and the for-navigation location map data read out from the storing means and displaying the position of the driver""s car detected in the position detecting means and a guiding route on the location map.
Therefore, a search calculation for a guiding route to roads placed in a facility in private land can be performed, and a guidance to a door of a building placed in the facility or a guidance to a recommended parking position placed in the facility can be performed. Also, a map matching with a location map of the facility can be performed in the driving of the car in private land which has a comparatively wide site, and positional precision of the driver""s car can be improved.
In a navigation apparatus according to the present invention, the facility information, which indicates the roads placed in the facility, is taken in the information taking-in means through a communication means.
Therefore, it is not required to make unnecessary increases to the capacity of the storing, means.
In a navigation apparatus according to the present invention, the facility information, which indicates the roads placed in the facility, is taken in the information taking-in means from a storage medium.
Therefore, it is not required to make unnecessary increases to the capacity of the storing means.
In a navigation apparatus according to the present invention, the facility information, which indicates the roads placed in the facility and is taken in the information taking-in means, is enciphered.
Therefore, an illicit use of the facility information, which is not open to the public, can be prevented.
In a navigation apparatus according to the present invention, the facility information includes a weighted value in a route from a destination placed in the facility to each of nodes, and a shortest route to the destination is calculated by comparing the weighted values of the nodes.
Therefore, because only one type of additional information denoting the weighted values of the nodes is included in the facility information, an amount of data can be reduced. Also, a shortest route can be calculated by only comparing the weighted values of the nodes, and it is not required to perform a complicated calculation. Also, the weighted value in a route from a connecting point to each node is registered in advance, so that a route calculation for a driver""s return can be performed in the same manner.